For example in a conventional image processing device as shown in FIG. 1 for example for character recognition there are mounted on a circuit board 1 a microprocessor 5 incorporating therein a comparison circuit 2, a dictionary ROM 3 and a program ROM 4. In this image processing device, dictionary ROM 3 stores feature values of a character, and when comparison circuit 2 receives a character of image data input, comparison circuit 2 compares it with the dictionary ROM 3 data, referring to the ROM 3 data. Microprocessor 5 refers to the program ROM 4 content to set a parameter for comparison circuit 2 for example for compressing and thus comparing input image data and also outputs a comparison result.
If in an image processing device of this type a system requires an additional function or it has a function to be changed, i.e., its version needs to be upgraded the device's non-volatile memory and microprocessor storing a program, data and the like therein need to be changed.
Accordingly, non-volatile memories, microprocessors and similar components that may be changed in the future are conventionally mounted on a circuit board via an IC socket and removed and inserted as required. Alternatively, a non-volatile memory, a microprocessor and the like that are soldered directly to a substrate are removed by melting the solder and another non-volatile memory, another microprocessor and the like are instead mounted on the substrate.
Exchanging components mounted on a circuit board via an IC socket, as conventional, however, is disadvantageous since:
{circle around (1)} If the IC socket's contact point is not clean it does not provide reliable contact, resulting in an erroneous operation;
{circle around (2)} The IC socket is large in size (particularly in its height direction) and is thus an obstacle in miniaturizing the equipment of interest;
{circle around (3)} Most of surface-mounting IC sockets have a structure with an IC lead held by a screw, a spring or the like. As such, vibration and hence impact would prevent the IC socket from providing reliable contact and thus cause an erroneous operation; and
{circle around (4)} Using an IC socket increases the cost.
Removing solder to remove a component and then again soldering another component is disadvantageous, since:
(a) Solder is melt by applying hot air to the substrate to heat it. As such, a wiring pattern corresponding to copper foil can peels and thus disconnects and the substrate can thus not be used. Furthermore, even if removing a component does not disconnect the wiring pattern, the heat applied would reduce the pattern's strength and the pattern thus could disconnect when the device being used vibrates and hence receives impact. In particular, for a surface-mounting component its mounting region does not have a hole, which would result in an insufficient strength and the copper foil readily peeling;
(b) If the hot air or the like heating the substrate also heats a component that does not need to be changed, the component could be damaged;
(c) If a component has a large number of pins, it is difficult to apply heat uniformly to all the pins and removing the component while preventing the above items (a) and (b) requires skill and a large number of process steps.
The present invention has been made to overcome the above disadvantages and it contemplates a device processing data such as images that ensures a high level of mounting-strength and is also readily capable of allowing for exchanging a component and upgrading a version.